The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
What Causes gradual weight management?
gradual weight management can happen for many reasons — some intentional through diet and exercise, others due to underlying health conditions. If you're losing weight quickly without trying, it's important to speak to your GP. For those actively seeking weight management in the UK, prescription options like Mounjaro and Wegovy are now available for eligible adults. This guide explains the causes of gradual weight management and explores how medication-supported weight management works in the UK healthcare system.
10,000+ calculations today · NHS-aligned thresholds · 100% free
Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
UK-Licensed Weight Management Options
Three prescription medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These GLP-1 and GIP/GLP-1 receptor agonist medications help regulate appetite and support feeling fuller after meals, typically resulting in weight loss alongside a reduced-calorie diet and increased physical activity.
Eligibility criteria: You may qualify if you have a BMI of 30 or above, or 27 or above with weight-related health conditions (type 2 diabetes, high blood pressure, cardiovascular disease, or sleep apnoea). For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds apply. Clinical trials showed Mounjaro supports an average weight loss of 15–21% body weight, while Wegovy supports approximately 15% — though individual results vary significantly.
Our GLP-1 weight loss calculator can help you estimate potential outcomes at different doses, and use our BMI calculator to check your personal BMI and eligibility range instantly.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
NHS vs Private Access in the UK
Access to prescription weight management medication in the UK depends on your route: NHS access is through tier 3 specialist weight management services, typically following a GP referral. Waiting lists vary significantly by region (ICB) and can be lengthy in many areas. Private access is available through UK-licensed prescribers via online consultations, without requiring NHS referral, though costs apply (typically £129–£320 per month depending on dose).
Your GP can advise whether you meet eligibility criteria and discuss the most suitable option for you. Track your weight loss journey using our free progress tracker once you've started a weight management plan.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
What counts as gradual weight management?
The NHS recommends losing 0.5–1 kg per week for sustainable results. Losing more than 1–2 lbs per week is considered rapid. Unintentional gradual weight management can signal underlying conditions and warrants a GP appointment. If you're using prescription weight management medication, faster loss is expected and monitored by your prescriber.
When should I see my GP about gradual weight management?
Contact your GP if you're losing weight without trying, losing more than 1–2 lbs weekly unintentionally, or experiencing other symptoms like fatigue, appetite loss, or changes in digestion. Rapid unintentional weight loss can indicate medical conditions needing investigation. Your GP can also assess whether prescription weight management is appropriate for you.
Can prescription weight loss medication cause gradual weight management?
Mounjaro and Wegovy can support faster weight loss than diet and exercise alone — clinical trials showed 15–clinically studied weight loss over 68–72 weeks. However, prescribers adjust doses gradually, and you should never exceed the recommended dose schedule. Results vary between individuals, and medication works best alongside dietary changes and physical activity.
How do I find out if I'm eligible for prescription weight management in the UK?
Check your BMI using our free BMI calculator on this page — if it's 30 or above, or 27+ with weight-related health conditions, you may be eligible. Book a GP appointment to discuss your options. Your GP can refer you to NHS specialist services or discuss private prescription options with you.
What's the difference between intentional gradual weight management and unintentional?
Intentional gradual weight management through medication is monitored and supported by a prescriber. Unintentional gradual weight management — losing weight without dieting or exercise — can signal illness, metabolic changes, or medication side effects. Always report unintentional weight loss to your GP for assessment and advice.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.